Identification of Optimal Tissue-Marking Dye Color for Pathological Evaluation in Fluorescence Imaging Using IRDye800CW

PurposeFluorescence-guided surgery using a tumor-specific antibody-dye conjugate is useful in various cancer types. Fluorescence imaging is a valuable tool both intraoperatively and postoperatively for ex vivo imaging. The color of inks used for tumor specimens during ex vivo specimen processing in pathology is an important consideration for fluorescence imaging since the absorption/emission of the dyes may interfere with the fluorescent dye. This study assesses suitable ink colors for use specifically with IRDye800CW fluorescence imaging.ProceduresEight tissue-marking inks or dyes (TMDs) commonly used for pathological evaluation were assessed. Agarose tissue-mimicking phantoms containing Panitumumab-IRDye800CW were used as an initial model. Mean fluorescence intensity was measured at 800 nm using both Pearl Trilogy as a closed-field fluorescence imaging system and pde-neo II as an open-field fluorescence imaging system before and after TMD application. An in vivo mouse xenograft model using the human head and neck squamous cell carcinoma FaDu cell line was then used in conjunction with TMDs.ResultsThe retained IRDye800CW fluorescence on Pearl Trilogy was as follows: yellow at 91.0 +/- 4.5%, red at 90.6 +/- 2.7%, orange at 88.2 +/- 2.2%, violet at 56.6 +/- 1.1%, lime at 40.9 +/- 1.8%, green at 19.3 +/- 2.8%, black at 13.3 +/- 0.6%, and blue at 8.1 +/- 0.2%. The retained IRDye800CW fluorescence on pde-neo II was as follows: yellow at 86.5 +/- 6.4%, red at 77.0 +/- 6.2%, orange at 76.9 +/- 2.8%, lime at 72.5 +/- 9.5%, violet at 59.7 +/- 0.4%, green at 30.1 +/- 6.9%, black at 17.0 +/- 2.7%, and blue at 6.7 +/- 1.7%. The retained IRDye800CW fluorescence in yellow and blue TMDs was 42.1 +/- 14.9% and 0.2 +/- 0.2%, respectively in the mouse experiment (p = 0.039).ConclusionYellow, red, and orange TMDs should be used, and blue and black TMDs should be avoided for evaluating tumor specimens through fluorescence imaging using IRDye800CW.